National Heart Lung and Blood Institute's, Boston University's Framingham Heart Study, Framingham, MA, USA; Departments of Cardiology and Preventive Medicine, Department of Medicine, Boston University School of Medicine, Boston, MA, USA; Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA.

Abstract

BACKGROUND:

The extent to which omega-3 fatty acid status is related to risk for death from any cause and for incident cardiovascular disease (CVD) remains controversial.

OBJECTIVE:

To examine these associations in the Framingham Heart Study.

DESIGN:

Prospective and observational.

SETTING:

Framingham Heart Study Offspring cohort.

MEASUREMENTS:

The exposure marker was red blood cell levels of eicosapentaenoic and docosahexaenoic acids (the Omega-3 Index) measured at baseline. Outcomes included mortality (total, CVD, cancer, and other) and total CVD events in participants free of CVD at baseline. Follow-up was for a median of 7.3 years. Cox proportional hazards models were adjusted for 18 variables (demographic, clinical status, therapeutic, and CVD risk factors).

RESULTS:

Among the 2500 participants (mean age 66 years, 54% women), there were 350 deaths (58 from CVD, 146 from cancer, 128 from other known causes, and 18 from unknown causes). There were 245 CVD events. In multivariable-adjusted analyses, a higher Omega-3 Index was associated with significantly lower risks (P-values for trends across quintiles) for total mortality (P = .02), for non-CVD and non-cancer mortality (P = .009), and for total CVD events (P = .008). Those in the highest (>6.8%) compared to those in the lowest Omega-3 Index quintiles (<4.2%) had a 34% lower risk for death from any cause and 39% lower risk for incident CVD. These associations were generally stronger for docosahexaenoic acid than for eicosapentaenoic acid. When total cholesterol was compared with the Omega-3 Index in the same models, the latter was significantly related with these outcomes, but the former was not.

LIMITATIONS:

Relatively short follow-up time and one-time exposure assessment.

CONCLUSIONS:

A higher Omega-3 Index was associated with reduced risk of both CVD and all-cause mortality.

Relations between quintiles of the Omega-3 Index and hazard ratios (+95% confidence interval) for death from CVD (n = 58), cancer (n = 146), other causes (n = 128), and all causes (n = 350, including 18 of unknown causes). Data are from 2500 participants free of baseline CVD followed for a median of 7.3 years. Adjusted for all variables in . P-values for trend are shown above the columns. CVD, cardiovascular disease; CHD, coronary heart disease.